Tuesday, 5 April 2016

Two Views of the Sun, via an iPad and Eclipse Filter

Two Views of the Sun, via an iPad with an Eclipse Filter

Here are a couple of pictures of the Sun, take with an iPad, through an “eclipse filter”.

The first was taken with the standard iPad camera app, with the lens covered by an eclipse filter, that I got during the last eclipse, from a university observatory.  The filter blocks almost all of the sun’s light.  I am not sure of the fraction of light allowed through, but suffice to say that nothing dimmer than the sun seems to make it through the filter.

The blend of colours is nice, especially the yellow around the limb.  This could be a manifestation of limb darkening, with the brighter interior pure white (CCDs saturated) and the darker limb showing the sun’s yellow frequency peak (CCDs not saturated).  Or maybe it is some other iPad optical response.

The next picture was taken with the iPad camera “stopped down” via an inexpensive app, available from the Apple app store.   The image was fairly small, so this enlargement is a bit pixelated.  So, the apparent detail around the edge of the sun is an artifact of image processing, rather than of the sun itself.

Someday, it would be nice to try this iPad photography during an actual eclipse.


Book one of the Witches' Stones series (Rescue from the Planet of the Amartos)

And here’s a (fictional) planet with a sun much hotter than our own, though still inhabitable:

“To help pass the tense minutes, Coryn studied the world outside the lone small window.  Greenery was planted outside the window, needed as a screen to protect the dwelling from the blazing white Kordean sun.   The leaves were thick and rubbery – unlike human beings, the plants that grew on Kordea could not escape the brilliant sun, so they had evolved a tough outer layer.  He reflected that this world was a fantastic mixture of the mystical, as represented by the seven moons, and the inescapably physical, as represented by the blistering Kordean sun.”

Plus, there's a nice neutron star on the cover, as well as a rather fetching heroine.  So, you should check it out :).

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